Showing 7 results for Heat Input
M. Sabzi, S. Moeni Far, E. Najafi Birgani,
Volume 1, Issue 1 (1-2016)
Abstract
In this investigation, the effect of heat input of SMAW process on the corrosion behavior of Hadfield steel weld joints was investigated. For this purpose, 4 annealed sheets with thickness 25 mm prepared from Hadfield steel and then welding applied by SMAW process with 6.75 and 11.25 kJ/mm heat input values. For corrosion behavior evaluation of base metal and weld metal areas, potentiodynamic polarization and electrochemical impedance spectroscopy methods were used in the 3.5% NaCl solution. The result of corrosion tests indicated that by increasing the heat input in the SMAW process, the corrosion resistance in the weld metal were reduced. It was also found that in both heat input values, base metal had more corrosion resistance compared to weld metal.
Y. Najafi , F. Malekghaini, Y. Palizdar, S. Gholami,
Volume 2, Issue 1 (8-2016)
Abstract
Recent research suggests that extraordinary combinations of strength and ductility can be achieved in the so-called TRIP steels. With the development of these steels, welding with small weld nugget size and acceptable strength are needed. For these reasons present study was carried out to investigate the effect of heat input onweld size, microstructure and the hardness of the welded metal of 0.4%C- 4%Al δ-TRIP steel after continues fiber-laser welding process. To achieve this goal a bead on plate welding with three different values of heat input 28, 60 and 80 J/mm were used.The results of welding process revealed that by increasing the heat input, cooling rate decreased and the volume percent of the δ-ferrite in weld metal increased due to the availability of sufficient time for partitioning of Al in high heat input which leads to the stable δ-ferrite and as a result the difference between the hardness of the weld metal in comparison to the base metal decreased.
M. Sabzi, R. Kalantaripour ,
Volume 2, Issue 1 (8-2016)
Abstract
In this investigation, the effect of heat input of SMAW process on the microstructure and mechanical properties of Hadfield steel weld joints was investigated. For this purpose, 4 annealed sheets with thickness
2 mm prepared from Hadfield steel and then welding applied by SMAW process with 6.75 and 11.25 kJ/mm heat input values. The evaluation of the microstructures of welding joints was conducted by optical microscopy and the joints mechanical properties were examined by tensile, charpy impact and microhardness measuring tests. The results indicated that by increasing the heat input in the SMAW process, microstructure consisted from smaller grains, and strength and microhardness increased but impact energy was reduced.
A. Mahab, M. Farzam, R. Dehmolaei,
Volume 4, Issue 1 (8-2018)
Abstract
The effect of heat input of submerged arc welding process on the corrosion bahavior of weld metal of API X42 gas pipeline steel weld joint was investigated. For this purpose, 6 annealed sheets of 15mm thickness were prepared from the X42 microalloyed steel. Submerged arc welding process with varying heat input of 37.8, 18.9 and 12.6 kJ/mm was used for joint welding. Then potentiodynamic polarization and electrochemical impedance spectroscopy methods were used to evaluate the corrosion behavior of the welded joints (in 3.5% NaCl solution). The evaluation of the microstructures of the welded metals in the weld joints were conducted using the scanning electron microscopy. X-ray diffraction was used for the analysis of the phases formed in the weld metal microstructure. Scanning electron microscopy observations and patterns obtained from the X-ray diffraction showed that the increase in heat input resulted in the increase in the amount of ferrite. The grain size also increased. Corrosion test results showed that by increasing the heat input of the weld process, the corrosion resistance increased..
B. Sadeghi, M. Shamanian, F. Ashrafizadeh, P. Cavaliere,
Volume 4, Issue 2 (1-2019)
Abstract
Solid state joining of powder metallurgy (P/M) processed and sintered by spark plasma sintering through friction stir welding (FSW) was studied. The nanocomposites were prepared via mechanical milling followed by spark plasma sintering. The microstructural and mechanical of the joints were evaluated as a function of the different processing parameters such as rotating and advancing speeds of the tool. The achieved finding revelled that the FSW of the nanocomposites produced by P/M containing bimodal sized Al2O3 reinforcement have a working window are affected by the heat input. The joint evolution revelled that the microstructure and mechanical properties of those was related to the generated heat input during the welding. It is known that dynamic recrystallization (DRX) caused grain size refinement of aluminium into stir zone. Meanwhile, it was revealed that the pinning effect of Al2O3 nanoparticles retarded grain growth of the recrystallized grains caused by dynamic recrystallization (DRX)
Mehdi Asle Taghipour, Reza Dehmolaei, Seyed Reza Alavi Zaree, Mohammad Reza Tavakoli Shoushtari,
Volume 7, Issue 1 (8-2021)
Abstract
The microstructure and mechanical properties of HSLA-100 steel weld joints was investigated. Welding with three heat input of 0.820, 1.176 and 1.392 kJ / mm was performed using E12018 electrode. Microstructural studies were performed using scanning electron and optical microscopes. The mechanical properties of welded joints were evaluated by impact and microhardness tests. Microstructural studies showed that with increasing the heat input, the amount of acicular ferrite in the weld metal decreased and the amount of polyhedral and quasi-polygonal ferrite increased. It was found that with increasing the heat input, the amount of layered bainite in the heat affected zone increased and the amount of granular bainite decreased. Due to the decrease in the amount of acicular ferrite in the weld metal microstructure with increasing inlet temperature, the amount of hardness and impact energy decreased. The results showed that the increase in heat input due to the reduction of the acicular ferrite of the weld metal and the dissolution of precipitates in the coarse grain heat affected zone has caused a decrease in hardness in these zones. It was found that with increasing the heat input due to decreasing the acicular ferrite, the impact energy of the weld metal decreased by 29% (from 45 joules at an heat input of 0.82 to 32 joules at an heat input of 1.392 kJ / mm). It was found that at all heat inputs, the impact energy of the base metal is greater than the impact energy of the weld metal.
Mehdi Mizabi Ask, Majid Belbasi,
Volume 9, Issue 2 (8-2024)
Abstract
In this study, the effect of heat input on the microstructure and mechanical properties of the joint of two dissimmilar steels D6AC and VCN 200 steel was investigated. For this purpose, the samples were welded with the current intensity of 130, 145 and 160 Ampers by GTAW process and using ER120 SG welding wire with a diameter of 2.4 mm. The metallographic results showed that the microstructure of the weld metal consisted of lath martensite and acicular ferrite phases, which increased the volume fraction of ferrite from 5 to 32% with the increase of heat input, and the morphology of the ferrite changed from acicular to polygonal ferrite due to the decrease in the cooling rate. The HAZ area microstructure consist of bainite, lath martenrite and ferrite. The highest strength value was obtained in the welded sample with low heat input. With the increase of heat input, the tensile strength has decreased from 1064 to 875 MPa. Also, with the increase of heat input, the impact energy has increased in the welding zone due to the increase of stable phases, and in the HAZ zone due to the growth of the primary austenite grains and the reduction of the grain boundary locking effect. The results of the fracture analysis showed that the fracture occurred in the weld zone with low heat input, brittle fracture, and in the HAZ area, combination of ductil and brittle fracture occurred. However, with the increase in heat input, dutil fracture occurred in the welding zone and brittle fracture occurred in the HAZ zone due to grain growth.
